The invention relates generally to a cleaning systems for spherical-shaped objects, and more particularly, to a method and system for handling and cleaning very small spherical-shaped objects suitable for use in the manufacture of spherical-shaped semiconductor integrated circuits.
Conventional integrated circuits, or "chips," are formed from a flat surface semiconductor wafer. The semiconductor wafer is first manufactured in a semiconductor material manufacturing facility and is then provided to a fabrication facility. At the latter facility, several layers are processed onto the semiconductor wafer surface. Once completed, the wafer is then cut into one or more chips and assembled into packages. Although the processed chip includes several layers fabricated thereon, the chip still remains relatively flat.
A fabrication facility is relatively expensive due to the enormous effort and expense required for creating flat silicon wafers and chips. For example, manufacturing the wafers requires several steps including making rod-form high purity polycrystalline semiconductor material, manufacturing a large single crystalline ingot from melted high purity polycrystalline semiconductor material in a quartz crucible, cutting the ingot into pieces (wafers), and lapping, polishing and cleaning wafers. Device fabrication processes thereafter include several high-temperature processes such as oxidation, doping, and diffusion, as well as chemical processes such as wet etching, chemical vapor deposition ("CVD"), chemical mechanical polishing ("CMP"), and photolithography process.
Another major problem associated with modern fabrication facilities for flat chips is that they require extensive and expensive equipment. For example, dust-free clean rooms and temperature-controlled manufacturing and storage areas are necessary to prevent the wafers and chips from defecting and warping. Also, these types of fabrication facilities suffer from a relatively inefficient throughput as well as an inefficient use of the silicon. For example, because the wafers are round and the completed chips are rectangular, the peripheral portion of each wafer cannot be used.
Therefore, due to these and various other problems, only a few companies in the world today can successfully manufacture conventional flat chips. Furthermore, the chips must bear a high price to cover the costs of manufacturing, as well as the return on initial capital and investment.
In co-pending U.S. Pat. No, 5,955,776 filed on May 16, 1997, assigned to the same assignee as the present application and hereby incorporated by reference as if reproduced in its entirety, a method and system for manufacturing spherical-shaped semiconductor integrated circuits is disclosed. As disclosed in the aforementioned patent application, the manufacturing process by which a spherical-shaped semiconductor integrated circuit device is produced may include a variety of processing steps.
Complicating the manufacturing process for spherical-shaped semiconductor integrated circuit devices are the special handling requirements which must be afforded the devices during their manufacture. Unlike conventional integrated circuits formed on flat surface semiconductor wafers, the integrated circuit may consume the entire surface area of the spherical-shaped semiconductor device. Also, unlike conventional integrated circuits which may be grasped along bottom or side surfaces thereof, grasping or otherwise contacting spherical-shaped semiconductor integrated circuit devices during the manufacturing process may result in significant damage. Furthermore, many of the processing techniques used to manufacture conventional integrated circuits are unsuitable for use in the manufacture of spherical-shaped semiconductor integrated circuit devices.
In particular, cleaning a spherical-shaped semiconductor substrate or integrated circuit device can not be performed in the same way as cleaning a relatively flat semiconductor wafer. Unlike conventional semiconductor wafers that can be placed in a container and sprayed or immersed with cleaning agent, the spherical-shaped semiconductor integrated circuit devices must be cleaned on all surfaces, with special care in the touching and handling of the surfaces. Also, unlike devices for cleaning other spherical shaped devices such as ball bearings, spherical-shaped semiconductor integrated circuits are extremely small, typically about 1 millimeter (mm) in diameter, and can be damaged very easily. The cleaning devices for ball bearings cannot be simply scaled down to this degree. Also, the spherical-shape semiconductor integrated circuits are extremely susceptible to scratches and other type of surface damage.
Therefore, the difficulties associated with the handling and cleaning of spherical-shaped semiconductor devices during the manufacturing process remains an obstacle to the development of such devices. Thus, there remains a need for a system and method capable of cleaning very small spherical-shaped semiconductor devices without damaging their outer surface.